This invention relates to a submarine propulsion system and specifically to a submarine propulsion system for an expendable unmanned underwater vehicle.
In attempting to dispose of underwater mines it has been usual to place an explosive charge adjacent the mine and then detonate the explosive charge hoping that this will cause sympathetic detonation of the mines warhead, destroying the mine, or at least render the mines sensor and triggering mechanisms inoperative, rendering the mine harmless. Placement of such charges has been carried out by a human diver or by a remote controlled submersible.
Both of these methods have drawbacks. The main drawback is the high risk to the diver or submersible and it is in fact due to the unacceptably high risk to the diver that submersibles are used. However the very high cost of a submersible able to carry an explosive charge to a mine location, deploy the charge adjacent the mine, and return to the mother ship makes loss of the submersible unacceptable, in addition the weight and bulk of the submersible is such that only a very limited number can be stowed aboard a warship and as a result the vessels mine sweeping capability could rapidly be lost due to destruction of the submersibles. A further disadvantage is that the time taken to dispose of a mine is by these conventional methods is quite long due to the need to get the diver or submersible to a safe distance before detonating the charge and the need for the diver or submersible to return to the mother ship, which must always remain at a safe distance from the mine throughout the operation, to pick up further explosive charges. Since the combined explosive effect of the mine warhead and the disposal charge may be very great the safe distance is relatively large.
It has been proposed to overcome these drawbacks by employing an expendable remote controlled submersible containing an explosive charge and simply moving the submersible into close proximity to a mine and detonating the charge, destroying the submersible and hopefully detonating the mine warhead or disabling the mine sensor and detonation mechanisms simultaneously. The bulk and expense of such an expendable submersible can be very much less than that of a conventional reusable submersible since there is no need to include any explosive charge deployment mechanism, the range and operational life need only be sufficient for a one way trip to the target mine and all of the control and power systems can be `one shot` devices.
In designing such an expendable submersible it has proved difficult to make the submersible easily and accurately controllable so as to ensure that it can be got into close proximity to the target mine before detonation while simultaneously keeping the submersible cheap and light so as to allow a large number to be carried aboard the mother ship and to allow large numbers to be purchased, the arrangement of motors and propellors to provide forward thrust and the necessary control surfaces to allow controlled horizontal and vertical movement of the submersible has proved particularly difficult.